57 lines
3.6 KiB
Markdown
57 lines
3.6 KiB
Markdown
Operator Boxes (MVP) — Stringify
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Overview
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- Goal: Extend “Everything is Box” to implicit operations by modeling them as explicit, observable Boxes.
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- Scope (MVP): Stringify operation used by print paths.
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- Status: Dev‑only; opt‑in via env flag; backward compatible.
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Quick Run
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- JSON only (Roundtrip + Nested): `./tools/opbox-json.sh`
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- Quick suite (dev, light preflight): `./tools/opbox-quick.sh`
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Flags
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- NYASH_OPERATOR_BOX_STRINGIFY=1 Enable StringifyOperator on print paths
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- NYASH_OPERATOR_BOX_COMPARE=1 Enable CompareOperator (observer) on compare ops
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- NYASH_OPERATOR_BOX_ADD=1 Enable AddOperator (observer) on Add binop
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- NYASH_OPERATOR_BOX_ALL=1 Enable auto-prelude injection for all operator modules (runtime convenience)
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- NYASH_USING_AST=1 Required to AST‑merge the operator modules automatically
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Parser tokens
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- Tokenizer accepts `~`, `<<`, `>>` in non‑strict mode (default). In strict_12_7, shift tokens are gated.
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- Unary `~x` parses to `UnaryOp(BitNot, x)`; binary `<< >> & | ^` parse via existing bit/shift rules.
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Behavior
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- Stringify: When the flag is ON, VM attempts to call `StringifyOperator.apply/1` before falling back to the legacy `to_string()`.
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- Compare (observer): When the flag is ON, VM calls `CompareOperator.apply/3` with `(op, a, b)` for observability, then performs normal compare semantics (operator result is ignored for now).
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- Add (observer): When the flag is ON, VM calls `AddOperator.apply/2` with `(a, b)` for observability, then performs normal add semantics (operator result is ignored for now).
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- The operators live under `apps/lib/std/operators/` and are auto‑injected into the AST prelude (dev only) so functions are materialized without changing user sources.
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Operator definitions (MVP)
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- Stringify — `apps/lib/std/operators/stringify.hako`
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- If `value` has `stringify()`, call it; else return `"" + value`.
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- Compare — `apps/lib/std/operators/compare.hako`
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- `apply(op, a, b)`; observer‑only for now, returns `true` and the VM performs the real compare.
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- Add — `apps/lib/std/operators/add.hako`
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- `apply(a, b)`; observer‑only for now, VM performs the real addition.
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- Sub/Mul/Div/Mod — `apps/lib/std/operators/{sub,mul,div,mod}.hako`
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- `apply(a, b)`; direct evaluation.
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- Bitwise/Shifts — `apps/lib/std/operators/{bitand,bitor,bitxor,shl,shr}.hako`
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- `apply(a, b)`; direct evaluation on integers.
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- Unary — `apps/lib/std/operators/{neg,not,bitnot}.hako`
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- `apply(a)`; negate / logical-not / bitwise-not.
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Design Notes
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- Backward compatible: existing programs run unchanged with the flag OFF (default).
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- Observability: with `NYASH_BOX_TRACE=1`, calls to the operator are visible as JSON lines (stderr), aiding diagnostics.
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- Rollback is trivial: remove the resolver injection and the two VM hooks; delete the operator file.
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Future Work (Optional / Later)
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- Elevate Compare/Add from observer to authoritative semantics behind stricter flags, once parity is verified.
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- Unify lowering (sugar → operator boxes) after VM and Builder parity are green.
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- Add per-operator adopt flags if needed for runtime switching; current builder call lowering already routes via operator boxes.
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Builder lowering (centralized)
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- Master flag: `NYASH_BUILDER_OPERATOR_BOX_ALL_CALL=1` lowers all arithmetic/compare/unary ops to `*Operator.apply` calls in one place (src/mir/builder/ops.rs).
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- Reentrancy guard: when building inside `*Operator.apply`, lowering is skipped to avoid recursion; falls back to direct MIR op.
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- Metadata: builder annotates result types (Integer/String/Bool) to preserve `value_types` so downstream analysis remains stable.
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